﻿// Artificial Intelligence for Humans
// Volume 1: Fundamental Algorithms
// C# Version
// http://www.aifh.org
// http://www.jeffheaton.com
//
// Code repository:
// https://github.com/jeffheaton/aifh
//
// Copyright 2013 by Jeff Heaton
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// For more information on Heaton Research copyrights, licenses
// and trademarks visit:
// http://www.heatonresearch.com/copyright
//

using System;

namespace AIFH_Vol1.Core.Distance
{
    /// <summary>
    /// The Euclidean distance is the straight-line distance between two points.  It is calculated by taking the
    /// square root of the sum of squares differences between each point in the vector.
    /// 
    /// http://www.heatonresearch.com/wiki/Euclidean_Distance
    /// </summary>
    public class EuclideanDistance : AbstractDistance
    {
        /// <inheritdoc/>
        public override double Calculate(double[] position1, int pos1, double[] position2, int pos2, int length)
        {
            double sum = 0;
            for (int i = 0; i < length; i++)
            {
                double d = position1[i + pos1] - position2[i + pos1];
                sum += d * d;
            }
            return Math.Sqrt(sum);
        }
    }
}
